The present invention relates to a process for extracting a gaseous component from a gas mixture, and more particularly, to an adsorption/desorption process for extracting oxygen from air.
Modern technology now allows microelectromechanical systems (MEMs) to be fabricated on semiconductor substrates. Various MEMs structures have been produced such as, accelerometers, micropumps, and micromotors. The size of these MEMs structures are measured in microns, and like transistors, millions of them can be fabricated at one time. The applications of these MEMs devices have increasing importance in fields where ltP size and weight reduction play an important role. Such fields include, but are not limited to: aerospace, aeronautics, military, and biomedics.
There are many instances where a concentrated form of a gas is needed, but where the weight and size of a conventional compressed gas tank is too prohibitive or where a location is too remote for conventional gas delivery means. For instance, certain medical situations require substantially 100% oxygen. Even though air contains oxygen (approximately 21%), it goes mostly unused and in cases of civil disaster or military combat, medical units must resort to using heavy, expensive and potentially dangerous tanks of limited compressed oxygen. In another instance, diver""s, and astronaut""s breathing times are limited, in part, by the amount of gases that can be carried. If a diver wants to dive for a longer period of time he must carry a larger, heavier tank of compressed gases.
It can be appreciated that a gas concentrator that is relatively small, lightweight, inexpensive, and safe would satisfy the above described need.
The present invention is an adsorption/desorption process and a microelectromechanical gas concentrator for extracting a gaseous component from a gas mixture. Specifically, the invention concerns an adsorption/desorption process carried out in a microelectromechanical gas concentrator comprising of an adsorption region, a desorption region, and an adsorbent that alternatively moves between both regions. In addition to other uses, the present invention may be used to overcome the problems described above.
The adsorption/desorption process of the present invention involves alternatively moving an adsorbent member between first and second regions, adsorbing a gaseous component from one of the regions with the adsorbent member, and desorbing the gaseous component from the adsorbent member into the other region.
The microelectromechanical gas concentrator of the present invention includes a single substrate divided into an adsorption region and a desorption region. It includes an adsorbent member that is alternatively movable between both regions and adsorbs a gaseous component from a gas mixture when in the adsorption region and desorbs the gaseous component when in the desorption region.
An advantage of the microelectromechanical gas concentrator is that it is extremely small when compared to conventional gas delivery methods where the gas itself must be ported. Its size would be measured in tens or hundreds of microns. A single gas concentrator, in accordance with the present invention, could provide oxygen to a single biological cell. Multiple gas concentrators, in accordance with the present invention, may be used together in parallel to produce a larger volume of oxygen, which may be integrated into portable systems, such as medical unit oxygen supplies.
Another advantage of the microelectromechanical gas concentrator is that, because of its size, it is relatively light in weight. Its use will reduce the need to carry heavy tanks of compressed gas into remote areas.
Yet, another advantage of the microelectromechanical gas concentrator is that, because of the microfabrication process used to produce microelectromechanical devices, the invention may be manufactured relatively inexpensively. Millions of the gas concentrators may be produced at once, on a single. wafer or substrate. These gas concentrators may be arranged in parallel (for increased volume) or in series (for increased concentrations). Individual gas concentrators could also be integrated into other microfluidic systems.
Yet, another advantage of the microelectromechanical gas concentrator is that, compared to a compressed gas tank, the present invention is much safer to operate, maintain, and store.
Yet, another advantage of the microelectromechanical gas concentrator is that it will operate essentially indefinitely. That is, it""s ability to provide a certain quantity of a concentrated gas is not dependant on a fixed volume container, such as a tank of compressed gas.
Still another advantage of the microelectromechanical gas concentrator is that, because of its size, it may be integrated into a portable respiratory apparatus, such as those used by divers or astronauts. This will allow the recirculation of exhaled oxygen back into the respirator, while releasing primarily excess carbon dioxide and nitrogen, substantially extending the useable operation/breathing time.
Still, another advantage of the microelectromechanical gas concentrator is that the pumping rate of the gas concentrator can be easily measured.
The previously summarized features and advantages along with other aspects of the present invention will become clearer upon review of the following specification taken together with the included drawings.